The anthill would be an aquatic monster.
At first they were only ants, then the flood came. It was huge, immense. Actually, the whole continent seemed to dive underwater. There was nowhere to go and most land animals died.
But ants don't die, they never die.
That was hundreds of millions of years ago, the ants never got back to the solid ground. They adapted, changed, coordinated more than ever.
Emphasized text should not necessarily be taken seriously.
Skeleton
The first anthills could not have survived without physical integrity. Air was still needed, so some ants became the anthill. First as an unorganized raft, then as more and more usefull backbones and limbs.
Bone ants are champions of gripping. Able to connect with each other in an extremely firm way, they form tubular structures (similar to those of the cytoskeleton of a cell) that can stretch from a few centimeters to several meters.
The interior of the tubes is reserved for "nervous" transmissions. The rest of the colony moves (and stays) on the anthill by grabbing the multiple handles the bone ants can provide.
The joints are more complex, some ants are specialized into sliding joints and some other ants are specialized into providing lubrication and maintenance.
Peripheric nervous system
As the food started to need effort (at first it was just eating the cadavers of those that can't survive into water), ants quickly needed to adapt. They needed to coordinate, quickly.
As stated before, the peripheric nervous system (PNS) goes inside the bones.
Inside the tubes are extremely elongated ants that most of the times stretch as long as the bone does. Their nerves are actually directly connected to the joint-ants.
The joint-ant has several nerves (and so several different way to activate), the main functions being:
- Controlling the joint rigidity
- Activating/relaxing the muscles
- Propagating back senses/pain
We now need to talk about...
Muscles
Food isn't always looking for you. Sometimes, you have to look for it. As in the water, ants could no longer go away from the colony, the colony had to move.
Compared to skeleton ants, muscle-ants are tiny. When a skeleton ant is usually 5mm long, a muscle-ant can rarely get to 0.5mm. Good thing there is a lot of them.
Muscle-ants don't transmit much chemical signal in the muscle process (they do in the building and repairing processes however). They mostly grip an ant before them and another behind them. They are mostly programmed to imitate on their behind-grip what happened to their front-grip. The delay caused by the "grip-transmission" gives the anthill a very flexible movement, adapted to swimming. Muscles constantly transmit how "hard" they find the stretching to be, signaling back the effort needed.
Tendon-ants are more complex, as they receive pheromone orders from the joints, initiate the grip with the muscles and maintain themselves within the joint. The latter is actually done thanks to their deformed antennas: they are stretched around the joint, at the same time ensuring reception of signals and physical connection.
Tendon themselves are about 2mm long and there is a lot of them on each side of the joint. Two of their legs are big in order to grip the bones, the other four are able to grip up to 30 muscles each.
Senses (and more on the PNS)
Moving is fine, and the colonies soon started following plankton gradients. But predators arose and the ants had bigger fish to hunt. Earing them was the key.
Throughout the skeleton, sensor-ants monitor chemicals (smell, taste) and mechanical (touch, sound) inputs as well as some other informations (heat, bubble presence, light-level).
These various senses are transmitted to the joints by courier ant that are constantly going through the bones. Each sensor is therefore connected to the two joints of its bone, allowing to approximately pinpoint the epicenter of the signals. Places that need a lot of precision simply have smaller bones, or, in very specific cases, directly connected joints.
Sensor information is first locally used by the joints. But let's see exactly how muscle activation works.
There are actually a lot of nerves just to activate one muscle, way more than for usual animals. They encode parameters for a big function, that function being mainly "how much grip to do with respect to the various senses, grip difficulty and your position in the skeleton tree".
This allows each node to be reactive while being centrally controlled.
Feeding of ants
The ants where now one, more than ever, they had to rely on each other to live. How could those proto-bones and proto-muscles be allowed to look for food?
Food is transported from the central digestive system to the limbs through simple worker ants. Bone and nerves having actually their mouths constantly connected to another ant's behind, the whole bone manages to feed itself through sharing.
Muscles, having a varying distance between each other, had to develop a different strategy. They made a friend! One very specific zooplankton has learned to live within the anthill at high concentrations. Good for the muscle ants, because the zooplankton learned to go by himself inside the tiny hard-workers belly and even pre-digest itself. Not that the plankton evolved to be stupid: being a prized guest in such a beauty has its perks.
Skin
What good is motion if you can't push water? For water movement and for the first time, ants needed surface.
Skin has a structure comparable to that of the bones, except it does not cycle on itself. The structure is weaker, and more flexible than bones. Dead ants are used as glue between skin-ants to augment impermeability.
Note that the colony is not covered in skin, it is only found where the anthill needs propulsion.
Eating and digesting
Where does the food come from? How could small ant eat big fishes? My mom told me no ant could eat me, but I never believed her. I know better.
A colony doesn't really have a mouth. More like a waterlock between the exterior and their stomach.
Outside the waterlock are lots of grabbing tentacles that push the food inside the hole. Remember the "some joints are directly linked together"? Tentacles.
The stomach itself is a big pocket. The "skin" ants glue themselves together (and to the bones) to provide a waterproof containment. Inside the stomach are the digesting ants. Former warriors made into highly chemically corrosive assailants and former workers cutting big pieces and transporting it to the exterior of the stomach. The non-edible materials are themselves used as cement and gravel to the glue surrounding the stomach.
Ant renewal
I tried to think about some joke about the Queen of the UK, but I found nothing worth it. Hey, have you noticed make less sense each chapter? Yeah, it's almost 4 am for me.
Right next to the stomach is the queen. The queen's job as not changed much since the colony still needs egg producing.
What's interesting though is that eggs are quickly moved out of the queen's chamber and placed where the final ant should be. A special pheromone as been developed to say "here's a new bone/muscle/nerve/other, make him hatch in the right spot". The need for ants is inferred through the analysis of the quality of food, muscular and bone input (or absence thereof, indicating a fracture) and some other and more obscure signals (of course it's more complex than that, it's alive!)
Reproduction
If the colony could not multiply, it could not evolve, and adapt, and survive. Anthills had to reproduce or be screwed. Am I a bad person? I'm not even ashamed.
Young future-queens are put at the farthest end of limbs and males have to go through the whole colony if they want to reproduce. Hijacking on their path workers and other ants. Only those with the material to perfectly communicate with the rest of the ants can get to transmit their genes.
Once impregnated, the now-queen hijacks nearby bone ants and detaches itself and its deserters to form a new entity. The first step of gestation is to create a proto-stomach and a chamber for the queen. Interestingly, the future stomach is also the gestating entity's placenta.
The hijacked ants having the signals from the mother colony, the baby can rely on its parent for food and shelter for a while. That is, until it has limbs too big to stay in the stomach. They then go out through the mouth-hole and the colony effectively becomes independent, killing the original renegades in the process of developing its own immune system.
Interestingly, some male ants may be able to impregnate females from other hills, providing there is direct physical contact between the two.
Central nervous system
The central nervous system is mainly required because fluid mechanics is weird. Like, super weird. Seriously, non-linear stuff.
The central nervous system (CNS) is a hive in itself. From birth until final death, it continuously grows. The neuron-ants have extremely small bodies and extremely long antennas. Each of their eight antennas (limbs were replaced) can reach up to a meter, effectively going through the whole brain, they basically work as axons. Neuron ants have some sort of hair that
mimics the function of dendrites.
The CNS and the stomach are stuck together through special extra-strong links that can transmit the best possible food. The queen's chamber is stuck on that "neck".
General morphology
This is either a text about the ant's history or something silly.
Colonies take very various shapes. From far enough, they look like black skeletal sharks. However, the oldest colonies often stop having a regular (or even symmetrical) shape. This is only possible when the colony is old, because younger colonies can maintain a regular pattern and only the biggest and well-trained brains can handle a complex asymmetric body.
You've read through all of that text? Wow. I wouldn't.